Kallikrein is a serine protease which is involved in blood pressure regulation and is overexpressed in primary aldosteronism. We hypothesized that quick quantification of this enzyme could represent a valuable diagnostic technique. Towards this aim, we demonstrate the use of an electrochemical approach to detect and quantify kallikrein for the first time. We designed the tripeptide Pro-Phe-Arg-pMA as a substrate for kallikrein and analyzed the enzyme concentration by measuring the release of the product, p-methoxyaniline (pMA), from kallikrein-mediated hydrolysis. Released pMA was detected by electrochemical measurement with a detection limit of 0.01 units/mL. The fit of the analysis of released pMA by chronoamperometry with Michaelis-Menten curves indicates that this technique offers quantitative detection.